In modern medicine, many medical apparatus are developed to acquire physiological signals from a living being by means of a medical electrode attached to the living being. For example, an ECG (electrocardiograph) device is widely used to acquire medical (i.e. biopotential) signals containing information indicative of electrical activity associated with the heart and pulmonary functions. An electrode is used to establish electrical connection between the ECG device and the skin of a living being, for example, a person or an animal and acquire physiological signals, which are one of the important bases for diagnosis of cardiovascular diseases or for monitoring cardiovascular and other physiological functions.
Stress Testing ECG is a diagnostic test performed on a person living with suspected or known cardiovascular disease, most commonly coronary artery disease (CAD). The stress testing procedure often requires the target person to exercise either on a treadmill or bike. Holter ECG is a diagnostic test performed on persons whose heart disease can only be detected through prolonged ECG monitoring or recording that normally takes 24 hours or even long. During Holter recording or monitoring, unavoidably, there would be frequent body movement of the person as a part of everyday life. To ensure quality of acquired ECG signals, both Stress ECG and Holter ECG require quality electrode to establish reliable electrical contact with the skin of the person.
FIG. 1 is an exploded perspective view of a conventional electrode used for an ECG device and FIG. 2 is a sectional view of the electrode of FIG. 1 when it is attached to the skin of a living being, for example, a person or an animal.
As shown in FIG. 1 and FIG. 2, an existing medical electrode 131 generally comprises an annular adhesive pad 133 having double-sided adhesive tape 147 and a central hole 137, a conductive pad 135 such as a foam pad filled with a conductive gel and disposed in the central hole 137 of the annular adhesive pad 133. The electrode 131 further comprises a first conductive snap element 139, a second conductive snap 141 and a sealing film 143 which is disposed between the first and second snap elements. The first conductive snap element 139 is to be attached to a first side 135a of the conductive pad 135, and be snapped into the second conductive snap 141. The outer portion of the sealing film 143 is attached to one side 133a of the annular adhesive pad 133.
The electrode may comprise a release liner 145, which is attached to a second side 133b of the annular adhesive pad 133 and can be removed before applying the electrode to a person. In use, the second conductive snap element 141 of the medical electrode 131 is snapped into a connector element C of a lead wire L, which transfers acquired signals to the ECG device.
Obviously exercising on a treadmill or bike, or body movements as part of everyday life may cause the lead wire L to move. When the lead wire L is fixed to the medical electrode, the mechanical force caused by the movement via the lead wire L will transferred from the first and second conductive snap elements and causes conductive pad 135 to move relative to the skin S of the living being, which in turn changes the electrical contact impedance between the conductive pad 135 and the skin S. This causes ECG signals distortion and introduces negative impact on ECG signal monitoring and diagnosis of relative disease.
To solve this problem, a known method is to use software algorithm to filter or correct the distortion or the interference after a noisy ECG waveform is acquired, but the software filtering may unexpectedly remove many ECG details due to lack of precise information of the movement causing such distortion. Thus, there is a need to provide an improved medical electrode for ECG devices, in particular, for Stress ECG and Holter ECG monitoring or diagnosis.